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以2014年四川省高考物理第7题为例分类探讨了物体离开传送带对应的多种可能性,为分析传送带这一类问题提供参考。 相似文献
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Currently, there is an increasing interest in and demand for training in a wide variety of nonclassical music--contemporary commercial music (CCM)--and most particularly for music theater. A survey of singing teachers was completed to elucidate their training, education, and experience with and methods of teaching CCM. Teachers were at colleges, universities, and conservatories as well as in private studios, both nationally and in several foreign countries. A substantial percentage of those teaching CCM had neither formal education in teaching it nor professional experience. Many of the respondents indicated conflict between classical and CCM styles. Respondents were generally familiar with voice science and voice medicine as well as certain CCM terminology. Teachers expressed an interest in obtaining more information, with an emphasis on healthy vocal production. These results are discussed, as well as implications for the singing teacher who desires specific training to teach CCM. 相似文献
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A mathematical model has been developed to simulate turbulent fluid flow and solidification in the presence of a DC magnetic field in an extended nozzle for metal delivery to a single belt caster. This paper reports on predicted effects of DC magnetic field conditions in modifying flows and solidification behavior in the metal delivery system. It is shown that the application of a DC magnetic brake to the proposed system can result in a reasonably uniform feeding of melt onto the cooled moving belt. This, in turn, optimises the rate of even shell growth along the chilled substrate. In order to account for the effects of turbulence, a revised low-Reynolds k–ε turbulent model was employed. A Darcy-porosity approach was used to simulate fluid flow within the mushy solidification region. Simulations were carried out for plain carbon steel strip casting. The fully coupled transport equations were numerically solved using the finite volume method. The computed flow patterns were compared with those reported in the literature. The performance of the magnetic flow control device proposed in this work is evaluated and compared with flow modifications obtained by inserting a ceramic filter within the reservoir. 相似文献
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辐射带中高能电子与空间甚低频电磁波由于波粒共振相互作用发生投掷角散射, 进而沉降入稠密大气而损失. 为研究甚低频电磁波对辐射带中高能电子的散射作用机制, 本文基于准线性扩散理论, 利用库仑作用和波粒共振相互作用扩散系数的物理模型, 得到了两组典型甚低频电磁波与高能电子波粒共振相互作用的赤道投掷角弹跳周期平均扩散系数, 并分析了甚低频电磁波共振散射作用与大气库仑散射作用对不同磁壳及不同能量的辐射带电子扩散损失的影响规律. 以磁壳参数L=2.2, 能量E=0.5 MeV的辐射带电子作为算例, 采用有限差分方法数值求解扩散方程, 计算分析了电子单向通量和全向通量随时间的沉降损失演化规律. 研究结果表明: 当电子能量大于0.5 MeV, 磁壳参数大于1.6时, 甚低频电磁波的共振散射作用显著; 随着磁壳参数或电子能量的增大, 斜传播甚低频电磁波引起的高阶共振相互作用越来越大; 电子全向通量近似随时间呈指数函数形式衰减. 相似文献
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章定国 《应用数学和力学(英文版)》1996,17(11):1059-1066
COMPUTERSIMULATIONOFTHEMOTIONOFTHEBULLETBELTOFAIRPLANEGUNZhangDingguo(章定国)(ReceivedMarch17,1995;CommunicatedbyWuRuifeng)Abstr... 相似文献
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Tan‐Hao Shi Shuo Tong Mei‐Xiang Wang 《Angewandte Chemie (International ed. in English)》2020,59(20):7700-7705
Linearly fused hydrocarbon nanobelts are a unique type of double‐stranded macrocycles that would serve as not only the powerful hosts in supramolecular science but also the templates to grow zig‐zag carbon nanotubes with defined diameters. Fully conjugated hydrocarbon nanobelts such as belt[n]arenes would also possess unique physical and chemical properties. Despite the importance, both fully conjugated and (partially) saturated hydrocarbon nanobelts remain largely unexplored because of the lack of cyclization methods. Reported here is the construction of nanometer sized H12‐belt[12]arenes based on the strategy to close up all fjords of resorcin[6]arene by means of six‐fold intramolecular alkylation reactions of resorcin[6]arene derivatives. All resulting H12‐belt[12]arenes produce a very similar nanobelt core structure with six benzene rings and six boat 1,4‐cyclohexadiene rings being alternately linear‐fused to give a nearly equilateral hexagonal cylinder. The average long diagonal is around 1 nm and the height of the cylinder is about 0.3 nm. The acquired H12‐belt[12]arenes would be the potential precursors to various hydrocarbon nanobelts including fully conjugated belt[12]arenes. 相似文献
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A novel method was developed for synthesizing ultralong SnO2 zigzag belts with the assistance of CuO powder. The crystalline structure and morphology of SnO2 zigzag belts were characterized using x‐ray diffraction, scanning electron microscopy and transmission electron microscopy. The growth mechanism of the ultralong SnO2 zigzag belts and the catalytic behavior of the copper were discussed. The humidity sensor based on as‐synthesized product shows high sensitivity and fast response time due to unique structure of the SnO2 zigzag belts with large surface‐to‐volume ratio. It can be found that the resistance of the SnO2 materials decreases obviously with increasing relative humidity (RH) at room temperature (26 °C). The results demonstrate that these SnO2 nanostructures are potential to be used as effective and high performance humidity sensors. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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